Electric heater element and method of making same



Feb. 4, BBQ, J, GREENLEAF 1,745,757

ELECTRIC HEATER ELEMENT AND METHOD OF MAKING SAME Filed July 30, 1926 Patented Feb. 1930 JOHN W. GREENLEAF, OF NEW UNITED STATES PRODUCTS CORPORATION,

PATENT OFFICE HAVEN, CONNECTICUT,

ASSIGNOR T ROCKBESTOS or NEW HAVEN, CONNECTICUT ELECTRIC HEATER ELEMENT AND METHOD OF MAKING SAME Application filed'J'ul y so,

- closed within a metallic shell or casing, This shell or casing is secured to a handle, generally entering the end ofthe handle a short distance. In some instances, an electrical switch mechanism is provided within the handle, and in others,"a lamp cord, whereby the device may be connected to a source of power. Terminals from the heating ele ment connect with either the switch mechanism or the lamp cord, usually within the handle, and these terminals are connected to the heating unit or are a part thereof. 7

Previous to this invention, considerable difficulty had been experienced in making the connection between the heating unit and the terminals therefor when such were separate parts. bulky to be inserted into the shell or casing of the device, and of fore, located within the handle. This arrangement required that the heating unit be extended into or closely adjacent to the han dle, and due to the heatingeifect thereof cause discomfort to the user and inconvenience in the use'of the device, the handle becoming uncomfortably warm, and in some cases charring where joined to the casing and thus becoming loosened therefrom.

One of the objects of this invention is to provide an electrical heating device of the character above described, wherein the above objections and disadvantages are obviated.

Another object of this invention is to provide an improved heating element for a heating device, said element being adapted to be enclosed within the casing of the device and having terminals extending without the casing, which terminals are joined to the heating unit in a novel manner whereby the j ointure is readily insertable within the casing. Still another object of this invention is i to provide an improved heating element for such devices, whereby all danger of insula' Usually, this jointure was too necessity was, there- 1926. Serial No. 125,968.

tion breakdowns and other causes of short circuits will be obviated.

Another object of this invention is to .de-

'velop a method of manufacturing the improved heating elements,-whereby the same may be produced economically and in quantit y to thereby reduce the cost thereof to a minimum.

To these and other ends, the invention consists in the novel features and combinations of parts and methods of manufacture and assembly, to be hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 illustrates one of the steps in the method of manufacturing the article of this invention;

Fig. 2 is a view of a heating unit;

Fig. 3 is a view of a terminal member;

Fig. 4 is a view illustrating the product after'a further step in. the method of manufacturing the article of-this invention;

Fig. 5 illustrates another step in the method of manufacturing the article of this invention; r

Fig. 6 is a view showing a portion of the product after the manufacturing step illustrated in Fig. 5;

Fig. '7 is a view of a heating element, embodying the features of this invention and before assembly within a casing;

Fig. 8 is an enlarged section on line 88- of Fig. 7;

Fig. 9 is an enlarged section on line 9,9 of Fig. 7;

Fig. 10 is a diagrammatic sectional view illustrating the method of assembling the heating element within a casing having a handle; and Fig. 11 is a somewhat enlarged longitudinal sectlon of the heating element as installed for use.

The heater element embodying the features of this invention and constructed according to the method to bedescribed herein, comprises a heating unit 18. The heating unit 18 preferably comprises a flexible insulating core 11, upon which is wound a suitable length of wire12 of relativelyhigh resistance. A machine for winding the resistance wire 12 upon the insulating core 11 is shown more or less diagrammatically in Fig. 1, wherein the material forming the core 11 is fed to a winding device 13 from a spool or spools 14. Preferably the core 11 is formed of the kind shown in Fig. 3. The terminal members 19 are formed by cutting ofi' prede-- termined lengthsof wire of relatively lowresistance, and simultaneously flattening the ends thereof as at 20.-

The lengths of wire wound core 18 as above provided, and the terminal members 19, are

then assembled together by means of metallic clips 21, which are wrapped about the abutting fiattened ends 20 of the terminal members 19 and the ends of the wire wound core lengths 18, as shown in Fig. 4. The clips 21 are securely crimped to both the wire wound core lengths 18 and to the terminal members 19, cooperating with the flattened ends 20 and the coils of the wire 12 to mechanically con nect the same, as well as to form a good electrical connection therebetween. The clips 21 are preferably made of thin metal and, therefore, do not appreciably increase the diameter of the heater unit at the point of jointure between the terminal members and the wire wound core. A continuous strip 'of assembled 'core lengths 18 and terminal members 19 is formedinthis manner, and subsequently wound upon a reel 22. i 1

The assembled wire wound core and terminal members are then fed from the reel 22 through a winding mechanism such as that shown diagrammatically in Fig. 5, where they are covered with a layer or plurality of layers of insulating material. In this instance, a plurality of layers are shown being wound upon the assembled parts. The insulating material preferably used is asbestos or other fibre roving having insulating properties and is wound upon the assembled parts by the rotatigighead 23 from the spools or reels 2 1 containing the same.

After the above mentioned covering has been formed upon the assembled parts, the same are preferably fed through a bath of impregnating material by means of a device 25. The impregnating material acts as a binder for the fibres of the coverin The strip of covered assembled parts is t eh fed through a wiper 26, which compresses the covering into a relatively thin and dense body 27, evenly surrounding the assembled parts. The covered assembled parts ard then collected upon a reel 28.

A portion of the product at this time, is illustrated in Fig. 6, and by severing the strip 29 of covered parts substantially at the central portion of each of the terminal members 19, the heater element 30, shown in Fig. 7, is formed.

When the heater element 30 is to be used for heating a curling iron or the like,it is bent back upon itself, and the loop portion 31 thereof is inserted into the shell or casing .32

' of the heating device, as illustrated in Fig.

10. i In this figure, it will be seen that the covered joint 34 is not of appreciably increased diameter and may be positioned well within the casing 32, and remote from the handle 33, thus obviating the disadvantages above referred to. The ends of the terminals 35 may be readily uncovered and joined to the source of power in any desirable manner. It will be further noted that the insulation covering about the entire heating element, due to the intermingled and impregnated fibres subsequently pressed into a dense and tight fitting body, forms a substantially single piece outer covering or casing. Such a covering is especially eflicient in preventing short circuits or the like between the coils of the resistance coil or the arms of the looped element or from the wire to the easing of the device. Although being as above described, dense and tight fitting, the covering does not in any way affect the flexibility of the elementto prevent sharp bending of the same, but allows such bends without the possibility of fractures or other damage thereto liable to destroy the insulating properties thereof.

Due to the crimping operation, whereby the clips 21 are secured to the terminal members 19 and to the Wire wound core 18, a good electrical connection is obtained therebetween without the disadvantage of causing an enlargement at the joint. The clip 21 securely retains both parts together by cooperating with'the fiattenedor headed end 20 of the terminal member 19, and with the coils of the re sistance wire 12 toprevent any looseness or possibility of separationtherebetween.

While I' have shown and described a preferred-form of heating element and the preferred steps and operations in the method of making the same, I do not limit myself to the specific-details shown or method employed, -as thesame may be modified and varied without departing from the spirit of the invention and the scope of the appended claims.

What I claim is: g

1. A heating element for electrical heating devices, comprising a core of flexible insulating material, resistance wire coiled about said core, a separate terminal member of high conductivityconnected to each of the ends of the over said coil and in reduced cross section over and along said terminal members, the

said heating element as a whole being flexible ductivity connected to each of the 'ends of terminal members,

said resistance wire, and acontinuous fibrous insulating outer covering extending over the resistance coil body and in reduced cross section over the major portions of the length of said terminal wires, said heating element as a whole. being flexible so that it can be readily looped or bent.

3. A heating element for electrical heating devices comprlsing a core of insulating material, a coil of resistance wire on said core, a conductive leading-in wire having a headed end, said headed end abutting the end of said core, and a metallic clip member wrapped about the core and in contact with the resistance coil, said clip member being also wrapped about the headed end of said leading-in wire to electrically connect said wire at the end thereof with said resistance coil.

4. The method of making electrical heating elements, which comprises winding resistance wire upon a flexible fibrous core member, cutting said wire wound coreinto shorter lengths, securing terminal members between the ends of said wire wound core lengths to form a continuous strip of joined together alternating wire wound cores and covering this product covering, and then cutting up the product into portions each consisting of one wire wound core with a terminal portion at each end thereof.

5. The method of making electrical heating elements, which comprises providing a length of resistance wire, cutting said wire into shorter lengths, disposing terminal members between the ends of said short wire lengths in abutment therewith and connecting the same together to form a continuous strip of joined together wires and terminal members, covering this strip with an insulating covering, and then severing the strip intermediate the ends of said terminal members to form short lengths of wire with'terminal portions at both ends.

6. The method of making electrical heating elements which comprises providing a length of coiled resistance wire, cutting said wire into shorter lengths, abutting terminal members to the ends of said lengths to form a continuous strip of alternating wire and ter minal members, electrically connecting said terminals and wire by wrapping a strip of metal about the abutting ends of both, covering this product with an insulating and flexible covering and then cutting up this with an insulating product into portions consisting of one length of wire with a portion of a terminal member at each end thereof.

7. A heating element for curling iron and the like, comprising a length of resistance wire coiled upon a flexible core member, a

terminal wire disposed at each end of said length of resistance wire with an enlarged end thereof in abutting relation therewith, a sheet metal conductor clip in clamping engagement with the end of said resistance coil and interlockedwith the adjacent enlarged end of said terminal wire to electrically and mechanically connect the same together, and

a flexible insulating covering "over all of said parts.

8. A flexible heating element adapted for insertion in looped form into a tubular casing, and comprising a coil of resistance wire, a terminal conductor wire having an enlarged endabutting the end of the coil, means-interlocked with the enlarged end of said terminal wire and clamping the end of said coil to electrically and mechanically secure the coil and terminal wire together, and a flexible fibrous insulating outer covering for the coil which extends over onto the terminal wire and is gradually reduced in cross-section from the coil embracing portion to the terminal embracing portion.

9. An electrical heating unit, comprising a flexible and yieldable core member of insulattional area than said resistance wire, each of said terminal wires having one end thereof headed and being disposed in longitudinal alignment with said core, with a headed end of the wire abutting an end of the core, an electrical conductor clip wrapped about each end of the resistance coil and the headed end of the adjacent terminal wire, to electrically and mechanically connect the same due to its clamping effect thereon, and a substantially one-piece flexible and insulating outer covering for said unit extending over said resistance wire and both of said terminal Wires. 10. A heating element for curling irons and the like, of resistance wire, a separate terminal wire of relatively high conductivity connected to each of the ends of said coil and extendin in substantial alignment with the axis of the coil, and a continuous and flexible insulating outer covering constituted by a snugly fitting sheath of compacted fibrous material extending over the coil body and in reduced cross section over the major portions of the length of said terminal wires, whereby the joints of said wires witlr said coil and the wires as well as the coil are encased therein, said heating element as a whole being flexible so that it can be readily looped or bent when applied to the heating appliance. 11. A heating element for curling irons and the like, comprising a helical coil of reone-piece sistance wire, a separate terminal wire of relatively high conductivity secured to and substantially abutting one end of the coil of resistance wire, and an outer snugly fitting insulating covering constituted by a sheath of matted and compacted insulating fibres, extending continuously over the coil body and in reduced'cross section over and along said terminal wire, said covering presenting a longitudinally and transversely continuous and homogeneous body and being readily flexible, said element as a whole being flexible so as to readily take a loop form.

12. A heating element for curling irons and. tlielike, comprising a coil of resistance Wire, a separate solid terminal wire of relatively high conductivity connected to each of the ends of said coil, and an outer snugly fitting insulating sheath extending continuously over the body of said resistance coil and the major portions of the length of said terminal wires, said sheath comprising a onepiece flexible body of matted and compacted insulating fibres, said element as a whole being flexible so that it can be readily looped or folded.

13. -An articlesuch as described, comprising a flexible wire coil or helix, a flexible terminal wire of less diameter than the coil-connected to each of the ends of said coil and extending axially from the latter, and an 7 outer insulating sheat-h extending over and conforming snugly to the outer surface of the coil and in reduced cross section to the terminal wires and encasing the joints between said wires and coil and the major portions of the length of said wires, said sheath being constituted by a flexible unitary homogeneous body of interentangling and compacted asbestos fibres, said articlev as a whole being readily' flexed without opening up the insulating sheath. I

14. A heating element for electrical heatingdeyices, comprising an elongated coil of resistance wire, separate elongated terminal member's-of high conductivity substantially in alignment with the axis of the coil at the respective ends of the latter, sheet metal conmechanical connection between the coil and terminal wire, said clip providing a joint of only slightly greater diameter than the coil, said joint tapering toward one end of the clip, and a snugly fitting flexible and continuous insulating covering for the coil and terminal wire which is gradually reduced in cross-section from the coil-embracing portion to the terminal-embracing portion so as to conform to the taper of said clip. 7

16. The method of making electrical heating resistances which comprises cutting a resistance Wire into suitable short lengths, in-

terpolating conductors between such lengths I to form a continuous strip, covering such strip with an insulating sheath, and then severing the strip at points between the ends of said conductors so as to produce a plurality ductive clips wrapped about the adjacent V ends of the terminal members and coil for insuring good mechanical and electrical connections with the latter, and a continuous and flexible insulating covering snugly encasing said coil, terminal members, and clips, and constituting the outer sheath of said=heating element, the latter as a whole, being sulficiently flexible to permit its insertion in looped form into its casing.

15. A heating element for curling irons I and the like, comprisingan elongated coil of resistance, wire, a terminal wire having an enlarged end abutting the end of the coil, a sheet metal clip wrapped around the enlarged end of the terminal wire and the adjacent end of the coil to obtain a good electrical and 

